The development of mobile communication devices is getting faster. With the vigorous development of the wireless wide area network (WWAN) and long term evolution (LTE) techniques, people have higher and higher expectations of mobile communication devices. Because many countries and regions adopt different types of communication systems, there are numerous wireless network systems in the market, such as LTE700/2300/2500, GSM850/900/1800/1900 and UMTS (Universal Mobile Telecommunications System). Therefore, a mobile communication device needs not only to be light, thin and compact, but also to cover multiband operations. The problem may be solved by for example, a mobile communication device being designed to utilize a coupling-feed technique so that its internal antenna achieves the characteristics of multiband operations. In addition to the mobile telephone communication networks, the communication device may also communicate with wireless networks (Wi-Fi), such as Wireless Local Area Network (WLAN), etc.
However, with the progress of communication technology, more and more operating bands are applied in communications, such that the mobile communication device needs to cover a wider and wider operating bandwidth and be able to roam between different communication frequencies.
Thus, a mobile terminal needs to handle and support increased number of frequency bands. The primary and secondary antenna when diversity or multiband antenna such as Multiple Input Multiple Output (MIMO) is used must also cope with the increased number of frequency bands. Besides, the requirement from the operators and users on the design of the terminal, especially in term of size, leads to smaller space for allocation the antenna. Designing good antenna demands implementation of some sort of antenna tuning. The antenna tuning may be implemented as an open loop tuning or as a closed loop tuning. Closed loop tuning is measuring the radio channel or use-case and tunes the antenna in a suitable way.
Due to increased complexity of modern communication networks, especially mobile phone network systems, the coexistence of multiple frequency bands and standards (e.g. 2G/3G/4g etc.) at least in the dense populated areas and the introduction of means for channel adoption in 3G (High Speed Downlink Packet Access (HSPA)) and 4G (LTE) using MIMO technology the demand for improved processing power in the terminal will drastically increase with higher power consumption as a consequence. Processing power is needed when initializing calls, e.g. for channels scans, roaming between networks, rake receiver parameter settings etc. These procedures may also represent some time consumption, which will delay the access to the network for end user.